Printing system wherein justification determination is shared between a host processor and a printer

Abstract

In a printing system comprising a printer controlled by a host processor (11), a system of justification is provided wherein the determination of justification parameters is shared by the host processor (11) and the printer formatting processor (12). Justification means (25) in the host processor (11) determine which spaces in a line are to be altered to effect justification. Means (26, 28 and 13) are provided for conveying data from the host processor to the printer indicating which spaces in a particular line are to be so altered, and means (42) are provided in the printer for determining the size of the indicated spaces necessary to effect such a justification.

We claim: 
     
       1. In a system comprising a printer controlled by a host processor, the improvement comprising, justification means in said processor for sequentially processing a data stream including, means for determining if a next unit in said data stream is a space unit,   means for storing a list predetermining which space units are alterable, and   means for determining from said list whether said next space unit is alterable,     means for conveying to said printer data indicating which space units are to be altered, and   means in said printer for determining the size of said alterable space units to effect justification.   
     
     
       2. The system of claim 1 wherein the size of said space units is determined in full character units. 
     
     
       3. The system of claim 1 wherein said host processor is primarily a data processor. 
     
     
       4. The system of claim 3 wherein the size of said space units is determined in units which are fractions of full character widths. 
     
     
       5. A method of justification in a printer controlled by a host processor comprising determining in said processor if a next unit in a sequential data stream is a space unit,   storing in said processor a list predetermining which space units are alterable,   determining from said list whether said next space unit is alterable,   conveying to said printer data indicating which space units are to be altered, and   determining in said printer the size of said alterable space unit to effect justification.   
     
     
       6. The method of claim 5 wherein the size of said space units is determined in full character units. 
     
     
       7. The method of claim 5 wherein said host processor is primarily a data processor. 
     
     
       8. The method of claim 7 wherein the size of said space units is determined in units which are fractions of full character widths.